Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin, 150001, P. R. China.
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130021, P. R. China.
Small. 2020 Oct;16(43):e2003799. doi: 10.1002/smll.202003799. Epub 2020 Oct 1.
It is absolutely imperative for development of material science to adjust upconversion luminescence (UCL) properties of highly doped upconversion nanoparticles (UCNPs) with special optical properties and prominent application prospects. In this work, featuring NaHoF @NaYbF (Ho@Yb) structures, sub-30 nm core-multishell UCNPs are synthesized with a small NaHoF core and varied Gd /Yb coexisting shells. X-ray diffraction, transmission electron microscopy, UCL spectrum, UCL lifetime, and pump power dependence are adhibited for characterization. Compared with the former work, except for a smaller total size, tunable emission in color from red to yellow to green, and intensity from low to stronger than that of traditional UCNPs is achieved for ≈10 nm NaHoF core size by means of changing number of layers and Gd /Yb concentration ratios in different layers. Besides, simultaneously doping Ho into the shells will result in lowered UCL intensity and lifted green/red ratio. Surface energy loss and sensitizing energy supply, which can be modulated with inert shielding of Gd and sensitization of Yb , are proved to be the essential determinant. More UCL properties of these peculiar Ho@Yb UCNPs are uncovered and detailedly summarized, and the findings can help to expand the application scope of NaHoF into photoinduced therapy.
绝对有必要调整具有特殊光学性质和突出应用前景的高掺杂上转换纳米粒子（UCNP）的上转换发光（UCL）性能，以促进材料科学的发展。在这项工作中，我们以具有 NaHoF@NaYbF（Ho@Yb）结构的特点，合成了具有小的 NaHoF 核和不同的 Gd/Yb 共存壳的亚 30nm 核壳 UCNP。我们采用 X 射线衍射、透射电子显微镜、UCL 光谱、UCL 寿命和泵浦功率依赖关系进行了表征。与之前的工作相比，除了总尺寸更小之外，通过改变不同层中的层数和 Gd/Yb 浓度比，还实现了 ≈10nm 的 NaHoF 核尺寸可调的从红色到黄色到绿色的颜色发射和从低到强于传统 UCNP 的强度发射。此外，同时将 Ho 掺杂到壳中会导致 UCL 强度降低和绿光/红光比值升高。表面能量损失和敏化能量供应，它们可以通过 Gd 的惰性屏蔽和 Yb 的敏化来调节，被证明是至关重要的决定因素。这些特殊的 Ho@Yb UCNP 的更多 UCL 性能被揭示并详细总结，这些发现有助于将 NaHoF 的应用范围扩展到光诱导治疗中。
